抗食源性病原菌细菌素的筛选及特性研究

目的 筛选一种抗食源性病原菌的细菌素,并对其稳定性进行研究.方法 以食源性病原菌Bacillus cereus ATCC 14579、Listeria monocytogenes LM201、Listeria monocytogenes LM605为指示菌,采用琼脂扩散法筛选细菌素产生菌,通过离子交换树脂法和高效液相色...     

Xmesh:一个mesh-like片上网络拓扑结构

针对片上网络(network on chip,简称NoC)的节点数量少、距离近、物理实现复杂度受到限制的特点,提出了一种新的Xmesh拓扑结构,并为该结构提出了XM路由算法.该结构在经典的mesh结构的基础上添加了两个对角线型的回边,缩短了节点间的距离,而且路由计算的复杂性不高,实现的复杂度基本没有增加.将Xmesh与经典的Mesh和Torus结构进行了理论分析比较,同时,在Popnet模拟器上基于均衡负载和热点负载两种负载模式进行性能比较.模拟结果表明,Xmesh平均延时不到Mesh结构的70%.对于均衡负载,当网络规模较小时,Xmesh的延时比Torus的更小;对于热点负载,当热点距离网络中心或者对角线比较近时,Xmesh的延时比Torus的小10%～30%.反之,其延时比Torus的大10%～30%.总的来说,Xmesh的性能与Torus比较接近,但其物理实现更为简单,Xmesh比Mesh结构的性能更好.     

基于PXI总线的工程车辆液压自动检测系统设计

介绍了一种工程装备液压系统性能自动检测系统.该系统以PXI总线系统构成硬平台,可更换适配器构成液压系统测试传感器与测试资源的物理连接与各种信号的调理,以LabWindows/CVI构成软平台,实现了从仪器自检-系统标定-自动检测-数据处理分析-打印测试报告等的自动化处理.实践表明,该系统拥有优良的可扩展性和工程实用性,在液压系统检测和故障诊断领域具有广阔的应用前景.     

基于事件驱动的单片机多任务程序设计

利用单片机进行嵌入式系统开发时,经常会面临同时处理多个任务的要求。为了在资源紧缺的单片机系统中获得资源与性能平衡的条件下,实现多任务处理机制,提出了一种基于事件驱动的单片机多任务程序设计方法。该方法内核设计简单、代码少、移植性好,可用于大多数带有定时中断的单片机系统,使一些复杂的单片机程序设计简单化,逻辑控制具有实时性。     

基于ARM虚拟化扩展的安全防护技术

近几年来,随着移动平台用户量的增加,移动平台安全成为安全领域关注的焦点.而ARM的虚拟化扩展,使得如何基于虚拟化技术进行移动平台的安全防护成为一个研究热点.本文首先介绍了虚拟化技术的分类以及早期的相关研究.然后,给出了ARM虚拟化扩展的相关概念,并与x86虚拟化扩展进行了对比.随后重点介绍了基于硬件辅助虚拟化技术的安全研究现状,主要包括通用的系统框架以及针对特定攻击的安全工具.最后,本文对基于ARM虚拟化扩展的安全防护技术的发展方向进行了展望.     

基于VPN技术的校园网安全防护

VPN技术是校园网中防御安全威胁的技术之一。通过对VPN技术的具体分析和研究,针对我校校园网络的情况,在校园网安全防护中部署了一种远程安全接入的SSL VPN和一种总校和分校之间信息安全传输的IPSec VPN,从而实现校园网内资源的安全访问。     

Vitamin D Deficiency Attenuates Acute Alcohol-Induced Hepatic Lipid Accumulation in Mice

Vitamin D deficiency has been frequently reported in chronic liver disease. However, its influence on hepatic lipid accumulation in alcoholic liver disease remains unclear. The present study investigated the effects of vitamin D deficiency on acute alcohol-induced hepatic lipid metabolism in mice. Mice were fed with vitamin D deficient diet, in which vitamin D was depleted for 12 weeks to establish an animal model of vitamin D deficiency. Some mice were administered a single gavage of alcohol (4 g/kg bodyweight) before they were euthanized. Results show that feeding mice with vitamin D deficient diet did not induce hepatic lipid accumulation. In contrast, vitamin D deficiency markedly reduced alcohol-induced triacylglycerol (TAG) content and prevented hepatic lipid accumulation. Moreover, vitamin D deficiency significantly attenuated alcohol-induced sterol-regulated element-binding protein (SREBP)-1c activation, which regulates genes for hepatic fatty acid (FA) and TAG synthesis, and the expression of its target genes fatty acid synthase (Fasn) and acetyl-coenzyme- A carboxylase (Acc). In addition, vitamin D deficiency alleviated alcohol-induced downregulation of hepatic nuclear peroxisome proliferator-activated receptor (PPAR)α, which governs FA transport and β-oxidation, and the expression of Carnitine palmitoyltransferase (Cpt)-1α, cytochrome P450, family 4, subfamily a, polypeptide (Cyp4a)10, and Cyp4a14, which are key enzymes for hepatic fatty acids β-oxidation and ω-oxidation. Taken together, these results suggest that vitamin D deficiency is not a direct risk factor for hepatic lipid accumulation. Vitamin D deficiency alleviates acute alcohol-induced hepatic lipid accumulation through inhibiting hepatic de novo fatty acid syntheses and promoting fatty acid β-oxidation and ω-oxidation.     

Studies on polymer latex films: II. Effect of surfactants on the water vapour permeability of polymer latex films

Poly(butyl methacrylate) films have been prepared from surfactant-free latices which had post-added commonly used latex stabilisers. Water vapour transmission rates were used to study film permeability in relation to morphology, which was also studied by freeze fracture replication transmission electron microscopy. The extent of latex coalescence depended upon the chemical nature of the stabiliser employed and at monolayer coverage was not necessarily deleterious to the barrier properties of the films.     

Self-sealing, autogenous healing and continued hydration: What is the difference?

It is well known that as concrete hydrates its permeability decreases. Continued hydration, however, is not the only mechanism which causes such reduction. Self-sealing, which is largely attributed to the dissolution and redeposition of hydrates, and autogenous healing of cracks, can also significantly reduce the flow. This paper reviews the relative effects of self-sealing, autogenous healing and hydration.